Francisco Marquez / Volunteer weighing a Greater flamingo (Phoenicopterus ruber) juvenile while another volunteer notes the data during the ringing process, Fuente de Piedra lagoon, Malaga, Spain. August.

Francisco Marquez / Volunteer weighing a Greater flamingo (Phoenicopterus ruber) juvenile during the ringing process, Fuente de Piedra lagoon, Malaga, Spain. August.

Edwin Giesbers / Eagle owl (Bubo bubo) chick on scales during ringing session. Netherlands. February 2016.

Edwin Giesbers / Man placing Eagle owl (Bubo bubo) chick on scales during ringing session. Netherlands. February 2016.

Edwin Giesbers / Man weighing Eagle owl (Bubo bubo) chick during ringing session. Netherlands. February 2016.

Suzi Eszterhas / Koala (Phascolarctos cinereus), male sick with chlamydia on scale while under anaesthetic. Currumbin Wildlife Hospital, Queensland, Australia, captive.

Suzi Eszterhas / Koala (Phascolarctos cinereus) Joey aged eight months, sick with urinary tract infection, on scales, Dreamland, Queensland, Australia, captive.

Solvin Zankl / [captive] Green toads (Bufo viridis) on scale, Lake Coghinas ( Lago di Coghinas) is an artificial lake, in northern Sardinia, Italy

Nick Upton / Common / Hazel dormouse (Muscardinus avellanarius) being weighed in a plastic pot on a mini balance during a survey by Backwell Enviroment Trust in coppiced woodland near Bristol, Somerset, UK, Octobe...

Cheryl-Samantha Owen / African penguin (Spheniscus demersus) egg being weighed, part of Chick Bolstering Project, Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), South Africa May 2012

Terry Whittaker / 2020VISION / Myotis bat probably a Daubenton's bat (Myotis daubentoni) being weighed inside a stocking, by researchers, Kent, UK, September 2010

Mark Hamblin / 2020VISION / Research scientist weighing Hen harrier chick (Circus cyaneus) Glen Tanar Estate, Grampian, Scotland, UK, June 2011